On Feb 8, 2018, at 3:44 PM, Jeff Squyres (jsquyres) <[email protected]> wrote:

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And the Fortran binding is

MPI_COMM_SPAWN_MULTIPLE(COUNT, ARRAY_OF_COMMANDS, ...) INTEGER COUNT CHARACTER*(*) ARRAY_OF_COMMANDS(*)

Note that the character*(*) syntax is archaic (as of 25+ years ago). The normal way of writing this is character(*).

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Intuitively, it seems obvious that 'array_of_commands' is an array of 'count' commands.

That is what I would assume. The user would be responsible for declaring the array elements large enough to hold the longest command. (All the elements of the array have the same length).

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That being said, the standard does not state that, and it is unclear whether 'array_of_commands' should be

NULL-terminated (so to speak) or not.

Fortran characters are NOT null terminated.

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Back to the Fortran binding, the following prototype, which is somehow consistent with 'array_of_argv',

could (help to) clear the confusion. The same comments also apply to the Fortran 2008 binding.

CHARACTER*(*) ARRAY_OF_COMMANDS(COUNT)

This is also fine, and clearer in terms of the expected minimum size of ARRAY_OF_COMMANDS. Cheers, Bill

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Bill Long [email protected] Principal Engineer, Fortran Technical Support & voice: 651-605-9024 Bioinformatics Software Development fax: 651-605-9143 Cray Inc./ 2131 Lindau Lane/ Suite 1000/ Bloomington, MN 55425